Alan, is it safe to assume you won't be using the DB from over the network and also locally again? I used to do the same thing with Emailer and it worked fine. But if Powermail isn't written to be able to recover from occasional failure to reach the DB or whatever the reason for not using this approach is, I suppose there is little we can do about it at the moment.
The best evolvement IMHO would be if IMAP was made transparent and a full citizen in some future revision.

